<?php
/**
 * Created by PhpStorm.
 * User: XD
 * Date: 2017/8/25
 * Time: 17:26
 */

class TestStatic
{
    protected static $_instance = null;

    public static function install(){
        if(TestStatic::$_instance){
            TestStatic::$_instance = new TestStatic();
        }
        return TestStatic::$_instance;
    }

    public static $wq = 0;

    function show(){
        echo self::$wq.PHP_EOL;
    }

    function add(){
        self::$wq = self::$wq+1;
    }

}